It is well known in various forms of electronic devices, including television receivers, that it is desirable to reduce the bandwidth of the device when the signal to noise ratio falls to objectionably low levels. One prior art system for controlling the receiver bandwidth is U.S. Pat. No. 3,633,119 Michael S. Balbes, granted Jan. 4, 1972. In that device a tuned filter was placed in cascade with an I.F. amplifier of a frequency modulated receiver. A control voltage, under manual control, varied the bandwidth of the filter. Human intervention is, of course, an apparent requirement in such a system and an obvious drawback in many situations.